The Gospel of Strength - Swami Vivekananda

You must retain great strength in your mind and words. "I am low, I am
low"--repeating these ideas in the mind, man belittles and degrades
himself.

Sin may be said to be the feeling of every kind of weakness. From this
weakness spring jealousy, malice, and so forth. Hence weakness is sin.

What we want is strength, so believe in yourselves... Make your nerves
strong. What we want is muscles of iron and nerves of steel. We have
wept long enough. No more weeping, but stand on your own feet and be
men.